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THE ROLE OF PHYSICAL HEALTH ON LIFE SATISFACTION IN PEOPLE WITH
SERIOUS MENTAL ILLNESS
A THESIS IN
Psychology
Presented to the Faculty of the University
of Missouri-Kansas City in partial fulfillment of
the requirements for the degree
MASTER OF ARTS
by
Amy Lee Barnes
B.A., University of Illinois at Springfield, 2007
Kansas City, Missouri
2011
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© 2011
AMY LEE BARNES
ALL RIGHTS RESERVED
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THE ROLE OF PHYSICAL HEALTH ON LIFE SATISFACTION
IN PEOPLE WITH SERIOUS MENTAL ILLNESS
Amy Lee Barnes, Candidate for the Master of Arts Degree
University of Missouri-Kansas City, 2011
ABSTRACT
The purpose of this study was to investigate the contribution of physical health and
mental health on quality of life reports in people with serious mental illness. Examining the
role of physical health is especially important in this population due to increased rates of
medical comorbidity. This study differs from previous research as it directly compares the
influence of mental health factors to physical health factors in a quality of life model. A
total of 49 participants completed a quality of life inventory, a health survey, and provided
subjective ratings of current clinical symptoms. Results indicate that people with SMI are
at least as concerned with their physical health as they are their mental health. Findings
further suggest that physical health is a stronger predictor of overall quality of life, even
after controlling for depressive and psychiatric symptoms, and limitations due to mental
health. Areas of future research are discussed.
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APPROVAL PAGE
The faculty listed below, appointed by the Dean of the College of Arts and Science
have examined a thesis titled “The Role of Physical Health on Life Satisfaction in People
with Serious Mental Illness,” presented by Amy L. Barnes, candidate for the Master of
Arts degree, and certify that in their opinion it is worthy of acceptance.
Supervisory Committee
Melisa V. Rempfer, Ph.D., Committee Chair
Department of Psychology
Jennifer D. Lundgren, Ph.D.
Department of Psychology
Jared Bruce, Ph.D.
Department of Psychology
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CONTENTS
ABSTRACT ................................................................................................................ ii
LIST OF ILLUSTRATIONS ......................................................................................... vii
LIST OF TABLES ....................................................................................................... viii
Chapter
1. OVERVIEW ....................................................................................................... 1
2. REVIEW OF LITERATURE............................................................................... 3
Quality of Life as Outcome Assessment ............................................................... 3
Quality of Life Reported by People with Serious Mental Illness .......................... 4
Correlates with Quality of Life ............................................................................ 6
Medical Comorbidity ........................................................................................... 8
Comprehensive View of Health ......................................................................... 10
Health Related Quality of Life ........................................................................... 11
The Current Study ............................................................................................. 12
3. METHODOLOGY ............................................................................................ 14
Participants ........................................................................................................ 14
Procedure .......................................................................................................... 14
Measures ........................................................................................................... 15
Quality of Life Enjoyment and Satisfaction Questionnaire ..................... 15
Short Form Health Survey ...................................................................... 16
Hamilton Depression Rating Scale ......................................................... 17
Brief Psychiatric Rating Scale-Expanded ............................................... 17
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Statistical Analyses ............................................................................................ 18
Hypothesis One ...................................................................................... 18
Hypothesis Two ..................................................................................... 18
4. RESULTS ......................................................................................................... 19
Descriptive Data ................................................................................................ 19
Data Analysis .................................................................................................... 22
Hypothesis One ...................................................................................... 22
Hypothesis Two ..................................................................................... 23
Secondary Model ................................................................................... 27
5. DISCUSSION ................................................................................................... 30
Limitations ........................................................................................................ 33
Conclusion ........................................................................................................ 34
REFERENCES ............................................................................................................. 36
VITA .......................................................................................................................... 42
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ILLUSTRATIONS
Figure Page
1. Role limitations due to physical and mental health among individuals with
serious mental illness 22
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TABLES
Table Page
1. Demographic Characteristics 20
2. Means and Standard Deviations for All Measures 21
3. Summary of Bivariate Correlations Among Quality of Life and the HAM-D,
BPRS-E, MHC, and PHC 25
4. Summary of R2 Changes at Each Step in the Hierarchical Regression 26
5. Summary of R2 and F Values at Each Step in the Hierarchical Regression Not
Controlling for Depressive Symptoms 28
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CHAPTER 1
OVERVIEW
The purpose of this study was to investigate predictors of quality of life in people
with serious mental illness (SMI). Quality of life measurement in people with SMI is an
evolving concept that consists of multiple domains including cognition, social and
occupational functioning, psychiatric symptoms, and health. While people with SMI
experience higher rates of medical comorbidity than the general population, quality of life
research to date has focused primarily on the mental health of people with SMI (Narvaez,
Twamley, McKibbin, Heaton, & Patterson, 2008), and neglected the domain of physical
health. Approximately 70% of people with schizophrenia have at least one medical health
condition and up to 33% have three or more concurrent health conditions. As such, the
early mortality rate among people with SMI is estimated at five times higher than the
general population (Kelly, Boggs, & Conley, 2007). Because of the high rate of medical
co-morbidities in this population, it is important to examine the effects of physical health,
in addition to mental health, on quality of life reports. This study investigated how
limitations due to physical health and mental health predict quality of life reports in people
with SMI. Including physical and mental health components into a unified view of overall
quality of life may better inform the currently fragmented system of medical and mental
healthcare for people with SMI (Miller, Pashall III, & Svendsen, 2006). Results found that
people with SMI reported lower quality of life than the general population, however did
not report significant differences between limitations due to physical health versus mental
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health. Physical health did emerge as the strongest predictor of quality of life, above other
factors such as depressive and psychiatric symptoms and role limitations due to mental
health. Overall the results of this study provide evidence of the effect of physical health on
quality of life and the importance of including physical health into comprehensive
treatment and intervention services for people with serious mental illness.
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CHAPTER 2
REVIEW OF THE LITERATURE
Quality of Life as Outcome Assessment
Quality of life in the serious mental illness literature is a broad concept
encapsulating many different domains including severity of psychiatric symptoms,
cognition, occupational and social functioning, physical health and the co-occurrence of
other psychiatric illnesses such as depression (Hewitt, 2007). Quality of life ratings by
people with SMI have been associated with differing levels of cognitive functioning, both
positive and negative psychiatric symptoms, access to social services, interpersonal
relationships, functional ability (occupational and daily living skills), and demographic
factors such as age, gender, education, and living situation (Matsui, Sumiyoshi, Arai,
Higuchi, & Kurachi, 2008; Narvaez et al., 2008).
Although current research in this area has failed to provide a uniform definition of
quality of life for people with mental illness, there are two general categories that have
been examined: 1) the subjective reports of people with SMI regarding the perception of
their own wellbeing, ability to function in daily life, and resources available to them and 2)
both subjective and objective reports of role limitations due to their mental health, physical
health and social and occupational functioning (Bow-Thomas, Velligan, Miller, & Olsen,
1999; Eack & Newhill, 2007). Subjective quality of life typically focuses on self-reports of
life satisfaction with family and social relationships, overall life satisfaction, and
functioning in activities of daily living. Subjective measures of quality of life also include
self-reports of severity of positive, negative and depressive symptoms. Objective quality of
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life indicators are typically observable factors such as employment, living situation, marital
status, and level of involvement in social activities (Narvaez et al., 2008). Current research
has found the integration of both objective and subjective quality of life indicators to be
more meaningful than examining either of them separately (Auquier et al., 2003).
Quality of life in people with SMI has become an important outcome assessment
for both research and treatment (Dickerson et al., 2008; Evans, Banerjee, Leese, & Huxley,
2007; Folsom et al., 2009; Narvaez et al., 2008). Whereas cognition and psychiatric
symptoms (both positive and negative) have typically been viewed as important objective
indicators of quality of life, the measurement of subjective quality of life may be more
meaningful in terms of improving overall quality of life in this population (Folsom et al.,
2009). Indeed, there has been a shift in the mental health system toward a more personal
recovery model that recognizes the importance of subjective experience (e.g., Andresen,
Caputi, & Oades, 2010). As quality of life becomes an important outcome goal in mental
health care and research, it is important to identify the primary domains that influence
subjective quality of life reports, especially in the SMI population (Evans et al., 2007;
Ritsner, Gibel, & Ratner, 2006).
Quality of Life Reported by People with Serious Mental Illness
Compared with the general population, people with mental illness report a lower
overall quality of life. Evans et al. (2007) compared quality of life ratings between people
with serious mental illness, people with common mental disorders (CMD) and people
without a mental health diagnosis in a two year longitudinal study. Participants with SMI
were included based on the presence of delusions, hallucinations, thought disorder, a
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psychotic illness of at least two years, and a minimum of two inpatient admissions related
to their mental health. Participants were categorized into the CMD group if they reported
moderate mental health symptoms. The control group reported no mental health symptoms
and was considered asymptomatic. Quality of life was assessed using the Lancashire
Quality of Life Profile (LQOLP) for the SMI group and the Quality of Life in the
Community Scale (QOL-COMM) for the CMD and controls. These instruments included
both subjective and objective assessment in life domains such as work, leisure, finance,
living situation, family, social life and health. Health was a broad domain encompassing
both mental and physical health combined. Significant differences were observed between
the control group and both the SMI and CMD groups. Further, in the majority of life
domains, the SMI and CMD groups did not significantly differ from each other. The
results of this research show that people with mental illness and those with common
mental disorders report lower quality of life ratings than the general population (Evans et
al., 2007).
Ritsner, Kurs, Kostizky, Ponizovsky, & Modai (2002) reported further evidence of
lower quality of life ratings using the Quality of Life Enjoyment and Satisfaction
Questionnaire (Q-LES-Q) and the Lancashire Quality of Life Profile (LQOLP) in people
with schizophrenia compared with people without mental illness. In this study, 199
participants with schizophrenia were administered a neuropsychological test battery and
were interviewed about current symptom severity and type (positive and negative). Results
indicate that for overall quality of life, individuals with schizophrenia reported
significantly lower subjective quality of life scores compared with control participants.
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Further analysis revealed that both measures were able to discriminate between persons
with and without mental illness in the specific domains of physical health, leisure activities
and social relationships. The Q-LES-Q was able to discriminate among groups in all
domains including health, work, leisure, social relationships, life satisfaction, perceived
quality of life index, subjective feelings, household duties and general activities. People
with SMI typically report their quality of life as significantly lower than the general
population (Ristner et al., 2002). As quality of life becomes an important target of outcome
research, identifying key differences in quality of life in the SMI population can help to
guide and focus current quality of life research.
Schechter, Endicott, & Nee (2007) also found that people with a history of mental
illness report lower quality of life ratings than people with no history of mental illness and
people with only one episode of mental illness. The results of this study found that people
who were currently mentally ill reported the lowest quality of life, followed by people with
a history of mental illness, who were not currently mentally ill. Quality of life was highest
in people with either no history or only one episode of mental illness. These findings
demonstrate not only that people with mental illness report lower quality of life than the
general population, but also that a history of mental illness, even in the absence of current
symptoms, is negatively associated with quality of life ratings.
Correlates with Quality of Life
To date, much of the research on quality of life in serious mental illness has
focused on its relationship with cognitive and clinical symptoms. With regard to cognitive
functioning, existing research generally indicates that quality of life may be only modestly
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related to cognitive functioning, however results are mixed. In current models, cognition
failed to continue to be a significant predictor with quality of life after adding other factors
such as clinical symptoms and medical comorbidity. Matsui et al. (2008) investigated the
effect of executive functioning and clinical symptoms on quality of life ratings in people
with schizophrenia. A total of 53 participants were given a battery of neuropsychological
tests. Clinical symptoms and quality of life were measured through interview by an
experienced clinician. Results showed that memory and social skill performance predicted
quality of life scores. Additionally, negative clinical symptoms (avolition and anhedonia)
were strongly negatively associated with quality of life scores. Interestingly, after
controlling for clinical symptoms, cognition was no longer strongly associated with the
participant’s quality of life ratings. Matsui et al. (2008) reported a small effect size when
examining the relationship between various neuropsychological measures and quality of
life impairment in people with schizophrenia.
These results are consistent with previous research by Wegener et al. (2005) who
also found moderate correlations between cognition and quality of life. Overall, however,
cognitive ability was less predictive of quality of life than were negative symptoms.
Negative symptoms, such as anhedonia or avolition, in people with SMI were more
strongly associated with quality of life than were positive symptoms. While previous
research has found a significant relationship between negative symptoms, severity of
symptoms and quality of life, the effect sizes were generally small and occasionally non-
significant when controlling for depressive symptoms (Eack & Newhill, 2007; Holloway
& Carson, 1999; Narvaez et al., 2008; Salokangas, Honkonen, Stengard, & Koivisto,
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2006), which can be difficult to differentiate from primary negative symptoms in people
with SMI.
Overall, research is inconsistent in its findings between symptomology and
subjective quality of life. Ritsner et al. (2006) found that improvements in quality of life
were positively correlated with reductions in clinical and depressive symptoms, however
Narvaez (2008) found that symptom reduction alone did not translate into better subjective
quality of life. In a meta-analytic review by Tolman and Kurtz (2010), effect sizes between
cognition, executive functioning and quality of life were generally small, suggesting that
there may be additional individual determinants of quality of life that may be more
meaningful. Ritsner et al. (2006) suggested that medical comorbidity may be an underlying
factor influencing both executive functioning deficiencies (including cognition) and lower
quality of life ratings. Ritsner recommended future research using integrated global and
health related quality of life measures such as the Q-LES-Q, which uses a broader domain
of health including both physical and mental health satisfaction.
Medical Comorbidity
Medical comorbidity is much higher in the SMI population than in the general
population and has become a focus of great concern (Kelly et al., 2007). Mortality rates in
the SMI population are much higher than among people without SMI. The current average
life expectancy of the general population is approximately 76 years; however, the life
expectancy of people with schizophrenia is only 61 years (Kelly et al., 2007). As a result,
serious mental illness is considered a life shortening illness. As much as 70% of people
with schizophrenia have increased rates of medical comorbidities and as much as 33% of
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this population suffers from at least three or more common medical disorders including
hypertension, chronic obstructive pulmonary disease, and diabetes which are all associated
with increased mortality rates and cardiovascular disease (Kelly et al., 2007).
Coronary heart disease (CHD) is currently the leading cause of death of all people
in the United States and people with SMI are at elevated risk (Kelly, et al., 2007). In the
general population, men have a 7.0% risk of developing CHD and women have a 4.2%
risk. However, people with serious mental illness show even greater risks with men having
a 9.4% risk and women having a 6.3% risk of developing CHD. Risk factors that influence
the development of coronary heart disease in the psychiatric population include lifestyle
factors, medication side effects and genetic predispositions (Kelly et al., 2007). These
factors are particularly challenging to address in the SMI population due to difficulties
with executive functioning, avolition, comorbid substance use, motivation, and lack of
integrated treatment of mental and medical health care.
Greater physical health symptoms are typically associated with greater mental
health symptoms. People with SMI have greater somatic concerns than the general
population and seek emergency hospital care significantly more frequently than people
without SMI (Hackman et al., 2006). Dixon, Postrado, Delhanty, Fischer, & Lehman,
(1999) found that the number of increased medical conditions was related to lower
subjective ratings of physical health, mental health and increased depressive symptoms.
Dixon et al. (1999) found that, consistent with the general population, people with SMI
also reported lower subjective quality of life ratings of both physical and mental health in
the presence of increased medical illness. Dixon et al. also showed that people with an
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increased number of medical illnesses were able to accurately rate their physical health as
poor. This level of accurate insight into physical health is noteworthy, in light of research
on the limits of insight into mental illness for this population (Karow et al., 2008). As
pointed out by Dixon et al. (1999), the inability to appropriately identify and describe a
mental health problem is distinct from inability to appropriately identify and describe a
medical health problem. Increased medical comorbidity, increased mortality and lower
subjective quality of life ratings provide evidence of the impact of poor physical health on
quality of life in people with serious mental illness.
Comprehensive View of Health
Co-occurring physical health problems, prevalent in the serious mental
illness population may represent a distinct area of concern when evaluating the general
domain of health, which typically encompasses both mental and physical health. Dickerson
et al. (2008) found that people with SMI and co-morbid Type II diabetes reported
significantly lower health related quality of life than people with SMI who did not have
diabetes. Interestingly, among those with diabetes, there were no differences in the mental
health domains of quality of life between people with and without a serious mental illness
diagnosis. These results are also consistent with research by Salokangas et al. (2006) that
showed people with schizophrenia and with severe physical illnesses reported significantly
lower subjective quality of life both at baseline and at a three year follow up than people
with schizophrenia without physical illness.
For this reason, recent quality of life research has focused on health related quality
of life measures, which integrate both physical and mental health domains. The 2008 study
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by Dickerson et al. purported to be the first in examining the impact of diabetes on
subjective quality of life ratings in people with SMI. Due to the positive relationship found
between physical health and quality of life and mental health and quality of life, it is
important to view health as encompassing both physical and mental characteristics. This
indicates an encouraging direction in SMI research incorporating physical health in
addition to mental health concerns specifically when looking at quality of life.
Health Related Quality of Life
Health related quality of life (HRQoL) measurement typically encompasses both
subjective perceptions and observable (objective) characteristics of health. Because people
with serious mental illness typically struggle with physical health issues in addition to
mental health issues, it may be more meaningful in this population to focus on health
related quality of life, which adopts an integrated view of health including both physical
and mental health limitations, rather than traditional quality of life measures. Originally
designed to measure the impact of chronic disease on quality of life in people with cancer,
HRQoL assessments have expanded into psychological research as an approach to
wellness that includes mental and physical health (Porzsolt et al., 1996). HRQoL is defined
as subjective reports of physical, emotional, cognitive and social and occupational
functioning, and is intended to capture a wider array of concerns than traditional global
quality of life assessments. This type of measurement is able to assess the impact of a
broad definition of health and its impact on subjective life satisfaction (Auquier et al.,
2003; Folsom et al., 2009; Porzsolt et al., 1996).
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Health related quality of life is distinct from global quality of life by addressing
physical and mental health separately, whereas the most recent definitions of global quality
of life represent overall life satisfaction, including three main dimensions of
satisfaction/wellbeing: biological, psychological and social functioning (Marwaha et al.,
2008). Quality of life is a developing concept. However, understanding the determinants
of subjective satisfaction in the serious mental illness population is important in order to
target areas for intervention. Specific to the SMI population, these include physical health,
psychiatric symptoms, cognition and activities of daily living (ADL) in addition to
demographic factors such as age, gender, education and socio-economic status. Currently,
the majority of quality of life research in the serious mental illness population has focused
primarily on mental health and social/occupational functioning. Recent quality of life
research is expanding to simultaneously examine clinical, cognitive and functional
predictors of quality of life, and health in the SMI population (Folsom et al. 2009; Narvaez
et al., 2008). Future research can utilize health related quality of life measures as outcome
assessments, thereby encompassing the physical and mental health care concerns of people
with serious mental illness.
The Current Study
The purpose of this study was to examine the effects of physical health and mental
health separately on subjective reports of overall quality of life in people with serious
mental illness. As discussed previously, the impact of physical health, in addition to mental
health, should be considered in psychological QOL research. Adopting an integrated view
of health using the construct of health related quality of life can facilitate the identification
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of individual predictors of life satisfaction, especially in the serious mental illness
population. Specifically it is predicted that among persons with SMI, satisfaction with
physical health will be lower than subjective reports of satisfaction with mental health. As
a result of increased physical illness in the SMI population, it is predicted that the physical
health component (PHC) of quality of life will be a stronger predictor of overall life
satisfaction than will the mental health component (MHC) even after controlling for the
effects of depression.
The first aim of this study was to determine if people with serious mental illness
more subjectively rate satisfaction with physical health as lower than satisfaction with
mental health. The first hypothesis was that people with serious mental illness would
report overall lower subjective satisfaction with their physical health than their mental
health.
A second aim of this study was to determine if role limitations due to physical
health concerns influenced quality of life ratings greater than role limitations due to mental
health concerns. It was hypothesized that the concurrent subjective satisfaction of physical
health of people with serious mental illness would be more predictive of overall life
satisfaction than would mental health.
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CHAPTER 3
METHODOLOGY
Participants
A total of 49 participants (24 female and 25 male) with serious mental illness, ages
18 to 65 (mean = 45.51 ±10.57), were recruited from a community mental health center
day program. Participants were included in the study if they had been previously diagnosed
with schizophrenia, schizoaffective disorder, bipolar disorder I or II, or major depressive
disorder (MDD). The Structured Clinical Interview for DSM Disorders (SCID; First,
Spitzer, Gibbon, & Williams, 1996) was used to confirm diagnosis. Exclusionary criteria
included known neurological disease, developmental disability, significant
sensory/physical impairment that would affect task performance (e.g. blindness), or
substance abuse/dependence in the prior 30 days. All study procedures received approval
from the institutional review board at the University of Missouri-Kansas City. This
research was conducted as part of larger study investigating cognition and everyday life
skills.
Procedure
Participants were recruited via case management staff at a community mental
health center. A brief phone screening was administered by researchers in order to
determine study eligibility. Testing was completed in a private room at the community
mental health center in one or two sessions totaling 3 to 5 hours. All participants provided
informed consent. In addition to a demographic profile which included a checklist of
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current medical conditions, participants also completed a quality of life inventory, and a
health survey. Participants also completed a measure of depression and were interviewed
about current psychiatric symptoms, as described below.
Measures
Quality of Life, Enjoyment, and Satisfaction Questionnaire
An abbreviated form of the Q-LES-Q, the Quality of Life Enjoyment and
Satisfaction Questionnaire (Q-LES-Q-18; Endicott, Nee, Harrison, & Blumenthal, 1993;
Ritsner, Kurs, Gibel, Ratner, & Endicott, 2005) was used to measure overall quality of life.
The Q-LES-Q-18 produces a general or overall quality of life index score, which was used
as the outcome variable for the purposes of this study. A total of 18 core questions address
physical health (items 1-4), subjective feelings (items 5-9), leisure time activities (items
10-12), social relationships (items 13-17) and satisfaction with medication (item 18). The
Q-LES-Q-18 also includes five additional questions that ask about overall satisfaction with
social relationships, the ability to function in daily life, economic status, overall sense of
wellbeing, and overall life satisfaction and contentment during the past week. The general
quality of life index score is derived by taking the average of scores for the first 18 items.
Ritsner et al. (2005) evaluated 339 participants with SMI and found the Q-LES-Q-
18 to be a highly reliable, valid and stable measure of self-reported life satisfaction.
Cronbach’s alpha was between .74 and .97 indicating a moderate to high internal
consistency. Construct validity was demonstrated through the ability of the Q-LES-Q-18 to
discriminate between participants with and without SMI, with control participants yielding
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higher mean scores (reporting higher quality of life). Test-retest reliability scores were
high, 0.90 for outpatient participants and 0.86 for control participants.
Short Form Health Survey
The Short Form Health Survey (SF-36; Ware, Snow, Kosinski, & Gandek, 1993) is
a 36 item generic measure of subjective health which includes questions about function
and dysfunction, distress, well-being, and both objective and subjective evaluations of
general health status (Hewitt, 2007). Widely used in many populations as a health related
quality of life assessment, the SF-36 contains two primary components, the physical health
component (PHC) and the mental health component (MHC), which were used as predictor
variables in predicting quality of life (Hewitt, 2007; Ware et al., 1993).
The SF-36 has extensive reliability and validity evidence, including research in the
serious mental illness population (Auquier et al., 2003; Burke, Burke, Baker, & Hillis,
1995; Hewitt, 2007; Pukrop et al., 2003). Internal consistency estimates for the general
population exceed 0.90 for both the PHC and MHC summary scales (Ware et al., 1994).
Median internal consistencies for the SF-36 dimensions are 0.79 (range 0.60 to 0.92) for
people with depression and 0.83 (range 0.71 to 0.89) for people with schizophrenia.
Discriminant validity is evidenced through correlational research showing a non-
significant relationship between psychiatric symptoms and quality of life ratings in people
with schizophrenia (Pukrop et al., 2003). Convergent validity is evidenced by strong
positive correlations between the SF-36 and the S-QoL (Schizophrenia Quality of Life;
Auquier et al., 2003), and MSQoL (Modular System for Quality of Life; Pukrop et al.,
2003). Intra-class correlations for test-retest reliability of the SF-36 (paper version) range
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from 0.54 to 0.88 among people with psychiatric symptoms (Burke et al., 1995). For this
study, the SF-36 scales of interest were the MHC and PHC, which were calculated into
standardized scores using means and standard deviations from the 1998 U.S. general
population norms. Standardized scores were created using the SF-36v2 software scoring
program. These scales share a common metric, with a range of 0-100, a mean of 50, and a
standard deviation of 10.
Hamilton Depression Rating Scale
The Hamilton Rating Scale for Depression (HAM-D; Hamilton, 1967) is a widely
used instrument designed to quantitatively assess the severity of depressive symptoms.
Consisting of 23 items, the HAM-D assesses multiple symptoms of depression including
suicidality, anhedonia, insomnia, anxiety, and feelings of helplessness and guilt. Higher
scores indicate more depressive symptomology. The HAM-D was chosen as a predictor for
this study because it is reportedly less sensitive to somatic complaints, common in the
serious mental illness population, than other measures of depression (Hamilton, 1967).
Brief Psychiatric Rating Scale- Expanded
The Brief Psychiatric Rating Scale-Expanded (BPRS–E; Lukoff, Nuechterlein, &
Ventura, 1986) is a rapid assessment of psychopathology symptoms. The BPRS-E is
administered via clinical interview and responses are scored on a 7 point Likert type scale
ranging from “not present” to “extremely severe”. Ratings of tension, emotional
withdrawal, mannerisms/posturing, motor retardation, blunted affect and
uncooperativeness are scored by the interviewer based on clinical observation. Ratings of
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conceptual disorganization, unusual thought content, anxiety, guilt, grandiosity, depressed
mood, hostility, somatic concern, hallucinations, and suspiciousness are provided through
self-report. Answers are scored from 1 to 7 for each item and a summative score indicates
current levels of psychopathology symptoms within the last two weeks. For the purposes
of this study, only the summative score was used as a predictor to assess current
psychiatric symptoms.
Statistical Analysis
Hypothesis One
The first hypothesis was that people with SMI would report lower satisfaction with
their physical health than their mental health. In addition to a total overall score, the SF-36
yields two sub-domain scores: a mental health component (MHC) and a physical health
component (PHC). A paired samples t-test was used to determine if there were significant
mean differences between reported satisfaction with physical health and mental health
scores on the SF-36.
Hypothesis Two
The second hypothesis predicted that physical health would influence overall
quality of life greater than mental health. In order to identify significant predictors of
quality of life in people with serious mental illness, hierarchical linear regression was used
with overall quality of life (Q-LES-Q) as the outcome variable and depression (HAM-D;
step one of regression), psychiatric symptoms (BPRS-E; step two), and role limitations due
to mental (MHC; step three) and physical health (PHC; step four) as predictor variables.
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CHAPTER 4
RESULTS
Descriptive Data
Of this sample, 46.9% (n=23) had a SCID-confirmed diagnosis of schizophrenia,
10.2% (n=5) with schizoaffective disorder, 28.6% (n=14) with major depressive disorder,
and 12.2% (n=6) with bipolar disorder. One participant did not fully complete the SCID,
but had a chart diagnosis of schizophrenia. Participants were primarily African American
(63.3%, n=31), followed by Caucasian (26.5%, n=13), and multi-racial (10.2%, n=5). The
majority of participants reported never being married (46.9%, n=23), and remaining
participants reported being either divorced/ widowed/separated (36.7%, n=18) or
married/living together (16.3%, n=8). Reported educational levels included some high
school (34.7%, n=17), high school graduate or GED (28.6%, n=14), post high school
(2.0%, n=1), some college (32.7%, n=16) and college beyond a bachelor’s degree (2.0%,
n=1). Most participants reported living independently (65.3%, n=32) while remaining
participants reported living with relatives (14.3%, n=7), living in supervised care housing
(12.2%, n=6), being homeless (6.1%, n=3), or living in a long term care facility (2.0%,
n=1). Approximately 91.8% (n=45) reported not being currently employed. See Table 1.
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Table 1. Descriptive Characteristics
Total N = 49 N (%)
Gender
Male 25 (51%)
Female 24 (49%)
Race
African American 31 (63.3%)
Caucasian 13 (26.5%)
Multi-Racial 5 (10.2%)
Marital Status
Never married 23 (46.9%)
Divorced/Widowed/Separated 18 (36.7%)
Married/Living together 8 (16.3%)
Education
Less than high school 17 (34.7%)
High school/GED 14 (28.6%)
Post high school/no college 1 (2%)
Some college 16 (32.7%)
College beyond 4 year degree 1 (2%)
Living Situation
Lives independently 32 (65.3%)
Lives with relatives 7 (14.3%)
Supervised care housing 6 (12.2%)
Long term care facility 1 (2%)
Homeless 3 (6.1%)
Vocational Status
Unemployed 45 (91.8%)
Employed 4 (8.2%)
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There were no significant group differences on predictor or outcome variables
based on diagnosis, age, race, marital status, or living status, however males reported
significantly lower HRQOL due to physical health than females. Means and standard
deviations for all primary measures are reported in Table 2.
Table 2. Means and Standard Deviations for All Measures
Total N = 49 Mean (SD)
Q-LES-Q 3.43 (0.60)
HAM-D 19.51 (10.50)
BPRS-E 44.92 (9.84)
MHC (n = 47) 39.38 (11.90)
PHC (n = 47) 42.76 (9.75)
NOTE: Q-LES-Q = Quality of Life Enjoyment and Satisfaction Questionnaire-23 (Score is
average of questions 1-18), HAM-D = Hamilton Depression Rating Scale, BPRS-E = Brief
Psychiatric Rating Scale-Expanded, MHC = Mental Health Component of the SF-36,
PHC = Physical Health Component of the SF-36.
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Data Analysis
Hypothesis One
A paired samples t-test was used to determine if participant’s standardized scores
on the PHC (M=42.76, SD=9.75) significantly differed from scores on the MHC
(M=39.38, SD=11.90) of the SF-36 health related quality of life measure. Our first
prediction was not confirmed and results showed that on average, PHC scores did not
significantly differ from MHC scores within the SMI sample, t(46)=1.40, p=.169, d=.29.
These results provide evidence that on average, participants did not report greater role
limitations due to physical health than mental health. See figure 1.
Figure 1.
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Hypothesis Two
Hierarchical regression was used in order to identify significant predictors of
quality of life in people with SMI. Quality of life (Q-LES-Q) was used as the outcome
variable and depression (HAM-D), psychiatric symptoms (BPRS-E), and role limitations
due to physical (PHC) and mental health (MHC) were predictor variables. Predictors were
entered in individual blocks with the HAM-D being entered in Step 1, the BPRS-E in Step
2, MHC in Step 3, and PHC in Step 4. The rationale for this order of entry included
controlling for the effects of depression and psychiatric symptoms on overall quality of
life. It was predicted that role limitations due to physical health would significantly predict
quality of life above what could be explained by depressive and psychiatric symptoms and
mental health factors, therefore MHC was entered prior to PHC. Results are summarized in
Tables 3 and 4.
Bivariate correlations revealed significant relationships among quality of life and
the following measures: the HAM-D (r = -.383, p<.05), the number of reported medical
conditions (r = -.481, p<.001), the MHC (r = .460, p<.001), and the PHC (r = .524,
p<.001). Demographic factors such as educational level, psychiatric symptoms as
measured by the BPRS-E, age, gender, race, marital status, living situation and work status
were not significantly related to quality of life scores in this sample. All correlations were
in the expected direction.
The overall regression, including all four predictors, was statistically significant, R
= .78, R2 = .61, adjusted R
2 = .57, F(4, 42) = 16.14, p<.001, indicating that overall quality
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of life scores were predicted quite well from this set of four variables, with approximately
78% of the variance in quality of life scores accounted for by the model.
To assess the contributions of individual predictors, the t ratios for the individual
regression slopes were examined for each variable in the step when it first entered the
analysis. In Step 1, depression was statistically significant, t(45) = -2.33, p<.05, R2 = .107.
Psychiatric symptoms as measured by the BPRS-E did not significantly increase R2 when it
was entered in Step 2, t(44) = -.193, p>.05, R2∆ < .001, F∆=.037. MHC scores significantly
increased R2 when it was entered in Step 3, [t(43) = 2.45, p<05, R
2∆ = .109, F∆=5.99]
indicating that less role limitations due to mental health significantly predicted higher
overall quality of life scores. PHC significantly increased R2
when it was entered into the
fourth and final step, [t(42) = 6.43, p<.001, R2∆ = .388, F∆=41.38] indicating that physical
health significantly predicted overall quality of life scores above what could be explained
by depressive and psychiatric symptoms and role limitations due to mental health. The
slopes of all predictors had the expected signs. Results are summarized in Table 4.
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Table 3. Summary of Bivariate Correlations Among Quality of Life and the HAM-D,
BPRS-E, MHC and PHC.
Quality of Life HAM-D BPRS-E MHC
HAM-D -.383**
BPRS-E -.255 .685***
MHC .460** -.656*** -.387***
PHC .524*** -.088 -.085 -.167
NOTE: HAM-D = Hamilton Depression Rating Scale, BPRS-E = Brief Psychiatric Rating
Scale-Expanded, MHC = Mental Health Component of the SF-36, PHC = Physical Health
Component of the SF-36. *p is significant at the 0.05 level (two-tailed), **p is significant
at the 0.01 level (two-tailed), ***p is significant at the 0.001 level (two-tailed).
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Table 4. Summary of R2 Changes at Each Step in the Hierarchical Regression.
B (SE) R
2∆ F∆
Step 1
Constant 3.765 (175)
HAM-D -.018 (.008) -.328* .107*
Step 2
Constant 3.384 (.401)
HAM-D -.017 (.011) -.302
BPRS-E -.002 (.011) -.038 .001 .037
Step 3
Constant 2.774 (.576)
HAM-D .001 (.013) .026
BPRS-E -.005 (.011) -.094
MHC .021 (.009) .441* .109* 5.99*
Step 4
Constant .374 (.557)
HAM-D .014 (.009) .255
BPRS-E -.006 (.008) -.096
MHC .034 (.007) .700**
PHC .039 (.006) .656** .388*** 41.38***
NOTE: One predictor entered in each step of the model in a user-determined sequence.
HAM-D = Hamilton Depression Rating Scale, BPRS-E = Brief Psychiatric Rating Scale-
Expanded, MHC = Mental Health Component of the SF-36, PHC = Physical Health
Component of the SF-36. *p is significant at the 0.05 level (two-tailed), **p is significant
at the 0.01 level (two-tailed), ***p is significant at the 0.001 level (two-tailed).
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Secondary Model
A separate hierarchical regression was used to identify significant predictors of
quality of life in people with serious mental illness, without controlling for depression.
Predictors were entered in individual blocks with the BPRS-E being entered in Step 1,
MHC in Step 2, and PHC in Step 3. The overall regression, including all three predictors,
was statistically significant, [R = .76, R2 = .58, adjusted R
2 = .55, F(3, 43) = 20.15, p<.001],
indicating that overall quality of life scores could be predicted quite well from this set of
three variables, with approximately 76% of the variance in quality of life scores accounted
for by the model. Psychiatric symptoms again were not able to significantly predict overall
quality of life [t(45) = .27, p>.05, R2 = .061], however both MHC [t(42) = 5.27, p<.001,
R2∆ = .157, F∆=8.80] and PHC [t(42) = 6.16, p<.001, R
2∆ = .367, F∆=37.99] remained
significant, even without controlling for depressive symptoms. Model summary is reported
in table 5.
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Table 5. Summary of R2 and F Values for the Model at Each Step in the Hierarchical
Regression Not Controlling for Depressive Symptoms
Predictors Included R
2 for Model F for Model F∆
BPRS-E .061 2.90
MHC .217 6.10** 8.80*
PHC .584 20.15*** 37.99***
NOTE: BPRS-E = Brief Psychiatric Rating Scale-Expanded, MHC = Mental Health
Component of the SF-36, PHC = Physical Health Component of the SF-36. *p is
significant at the 0.05 level (two-tailed), **p is significant at the 0.01 level (two-tailed),
***p is significant at the 0.001 level (two-tailed).
Additional Analyses
A separate one sample t-test revealed that participants’ standardized PHC scores
[t(46)=-5.086, p<.001, d=-1.05] and MHC scores [t(46)=-6.116, p<.001, d=-1.26] were
lower than standardized population PHC and MHC scores (M=50.00, SD=10.00). These
results are consistent with previous research showing lower health related quality of life in
people with SMI compared with the general population (Evans et al., 2007; Folsom et al.,
2009; Ritsner et al., 2002; Schechter et al., 2007).
Bivariate correlations revealed significant associations between the MHC of the
SF-36 and with years of education (r = .332, p<.05), positive and negative symptoms as
measured by the BPRS-E (r = -.387, p<.01), and depressive symptoms as measured by the
HAM-D (r = -.656, p<.001). Bivariate correlations also demonstrated a significant negative
relationship between the PHC of the SF-36 and the number of reported medical conditions
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(r = -.464, p<.001). Age, gender, race, marital status, living situation and work status were
not significantly related to MHC or PHC scores in this sample.
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CHAPTER 5
DISCUSSION
The purpose of this study was to investigate the predictive ability of the PHC of the
SF-36 on subjective quality of life in people with serious mental illness. Previous quality
of life models have shown mixed results when investigating the factors that influence QOL
in this population. Due to the high prevalence of medical comorbidity, and research within
the general population showing lower quality of life among people with physical health
limitations, this study examined health related quality of life due to physical health factors
as distinct from mental health factors. This study differs from previous research in that it
directly compared self-reported role limitations due to physical health to self-reported role
limitations due to mental health.
The first hypothesis for this study, that participant’s reports of role limitations due
to physical health would be higher than role limitations due to mental health factors, was
not supported. Although there were no differences in the MHC and PHC scores of the SF-
36, these results are still meaningful as they show that people with SMI are at least as
concerned with their physical health as they are their mental health. Compared with the
general population, health related quality of life in this sample was significantly lower, and
is consistent with previous research. These results demonstrate that people with SMI report
as many role limitations due to physical health as they do mental health. The recognition of
physical health care needs is consistent with national and state mental health initiatives
which utilize both mental health and physical health as part of a whole-body approach to
wellbeing.
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In order to investigate the relative contribution of physical health in subjective
QOL, the second hypothesis proposed that physical health of people with SMI would be
more predictive of overall quality of life than would mental health. In the current model,
the PHC was able to explain a substantial amount of variance in quality of life scores
beyond what was already explained by mental health factors. Depressive symptoms, role
limitations due to mental health, and role limitations due to physical health significantly
increased the predictive ability of an overall QOL model, and independently, were
significant related to quality of life. Positive and negative symptoms, as measured by the
BPRS-E, did not significantly add to the explained amount of variance in the model.
Correlational analyses also failed to demonstrate a significant relationship between
psychiatric symptoms and quality of life, which is consistent with previous research
(Ritsner et al., 2006). Although role limitations that people experienced due to mental
illness did influence overall quality of life ratings, the role limitations people with SMI
experienced due to physical health was significantly more distressing. Overall, 78% of the
variance in quality of life scores was explained from this proposed model. Consistent with
hypothesis two, PHC provided the strongest unique predictive contribution to subjective
QOL even after controlling for other predictive factors such as depression and mental
health.
Depression was included as the first predictor in the model in order to capture its
unique contribution to overall quality of life. Independently, greater depressive symptoms
were predictive of lower quality of life, however this relationship did not remain
significant with the inclusion of positive and negative symptoms and health related quality
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of life scores. Depression and quality of life were negatively associated, indicating that
people who reported greater depressive symptoms also reported a lower quality of life.
These results provide evidence that although depression and quality of life are strongly
related, additional factors such as physical health also have a strong influence on subjective
quality of life.
MHC also emerged as a significant predictor of overall quality of life even after
controlling for symptoms. The MHC component of the SF-36 is comprised of questions
related to overall mental health, energy and fatigue, social functioning, and role limitations
due to mental health problems. Because people with serious mental illness typically report
difficulties in these life domains, this finding was not unexpected, and highlights areas to
target for intervention and research. Construct validity for the model is supported with
MHC emerging as an independent predictor in the proposed model, as it would be
expected that people with serious mental illness would also report significant role
limitations due to mental health.
Most importantly, and the overall purpose of this study, was that PHC was able to
significantly predict overall quality of life scores after controlling for the effects of
depression, psychiatric symptoms, and mental health factors. The PHC component of the
SF-36 is comprised of questions related to general health, physical functioning, bodily
pain, and role limitations due to physical health problems. This is especially noteworthy
given that the mean scores of role limitations due to physical and mental health were not
significantly different, indicating a stronger effect of physical health, rather than mental
health, on quality of life. Given the high rates of medical co-morbidity, it may be more
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meaningful to focus on health -related quality of life, as measured by the SF-36 in a SMI
population.
Interestingly, in a second regression model that did not control for the effects of
depression, positive and negative psychiatric symptoms independently were not a
significant predictor of quality of life, however MHC and PHC continued to explain up to
76% of overall quality of life scores. This model also continued to show physical health as
the strongest predictor of quality of life. Interpretation of this model suggests that although
depressive symptoms are a unique contributor to overall quality of life, physical health
remains a distinct area of concern affecting quality of life in people with SMI.
Limitations
One of the primary limitations of this study was the lack of statistical power to
include additional predictors in the model. Previous research has shown both community
and social functioning as being significantly related to quality of life in people with SMI,
however this limited sample size did not allow for testing of additional predictors (Test et
al., 2005; Tolman & Kurtz, 2010). Other published quality of life models have found a
significant effect of social factors on quality of life in people with SMI. For example,
Dufort, Dallaire, & Lavoie (1997) found that an effective social support network was able
to independently account for 16% of overall variance in a six factor global quality of life
model. It is therefore important to note that the model proposed in the current study is not
comprehensive, but represents the role of more global factors (overarching mental health
and physical health) that impact quality of life. Future research should include additional
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known predictors of QOL into a more comprehensive model including physical, mental
and social factors.
A further limitation of this study is that generalization may be weak within the SMI
community. The participants in this sample were all participating in a formally structured
outpatient day program with convenient access to medical care, mental health care and
case management. As such, the results of this sample may not be replicated in individuals
in other contexts. However, it could be hypothesized, that in a less comprehensive
treatment environment, people without access to health care would most likely report even
greater difficulties due to physical and mental health, which would further strengthen the
model. Further research should help clarify the potential role of health care access on QOL.
Also, variance explained in the model by physical health may be artificially inflated
due to item overlap between the PHC component of the SF-36 and the Q-LES-Q that is not
present within the MHC. Specifically, the Q-LES-Q contains a subdomain of physical
health that includes four of the 18 total items. Therefore, internal validity may be
weakened by using this particular health survey in order to predict overall quality of life.
Last, accuracy of data collected by self-report is questionable, and much of the data
in this study was subjective, which may differ from objectively measured mental and
physical health. It could be argued, however, that subjective assessment of quality of life
may be the most meaningful constructs to capture in QOL research.
Conclusion
Overall, outcome research has revealed that improvements in cognition, reduction
of psychotic symptoms, and access to social services may be necessary, but not sufficient
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methods of improving quality of life in people with serious mental illness (Test et al.,
2005; Tolman & Kurtz, 2010). Physical illness has become a cornerstone feature of serious
mental illness, and an overwhelming body of evidence shows that individuals with SMI
have increased mortality rates more than five times higher than the general population
(Kelly et al., 2007). In light of current findings, researchers and clinicians should focus on
a comprehensive view of health, addressing both the mental and physical health concerns
and limitations in people with serious mental illness. There is growing recognition that
recovery and QOL improvements are realistic goals for persons with schizophrenia and as
such, there is a need for research on relevant outcomes such as people’s subjective
experience of quality of life. Current quality of life research indicates increasing concern
and self-reported dissatisfaction with physical health (Dufort et al., 1997). As quality of
life becomes an important goal for outcome research, incorporating physical health into a
comprehensive model of overall wellness may have positive implications for recovery
among persons with SMI. Given the importance placed on subjective and recovery-based
treatment orientations, it is important for research to continue to explore the strengths and
limitations of quality of life measures in persons with SMI.
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VITA
Amy Lee Barnes was born on August 1st, 1972 in Memphis, TN. She was educated
in the public school system in Springfield, IL where she graduated from Lanphier High
School in 1990. Amy attended the University of Illinois at Springfield and was a member
of Psi Chi national honor society in psychology, including holding the office of Vice
President of Psi Chi. Amy presented at several academic conferences and received the
Independent Student Research Recognition Award in addition to the Undergraduate
Student Research Grant. Amy earned her Bachelor of Arts degree in 2007 and graduated
Magna Cum Laude with a major in Psychology.
Prior to graduation from UIS, Amy was accepted to the Clinical Health Psychology
program at the University of Missouri – Kansas City. She began the program in Fall 2007.
Since that time Amy has contributed to several poster presentations and one published
work in the Journal of Pharmaceutical Education. Amy has been awarded the Gerre Gene
Strauss research award and the Audrey Langworthy research award. Amy is currently a
member of the Association of Cognitive and Behavioral Therapies and the American
Psychological Association.